Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: trigexpand (<expr>) Expands trigonometric and hyperbolic functions of sums of angles and of multiple angles occurring in <expr>. For best results, <expr> should be expanded. To enhance user control of simplification, this function expands only one level at a time, expanding sums of angles or multiple angles. To obtain full expansion into sines and cosines immediately, set the switch trigexpand: true.

trigexpand is governed by the following global flags:
trigexpand If true causes expansion of all expressions containing sins and coss occurring subsequently.
halfangles If true causes half-angles to be simplified away.
trigexpandplus Controls the "sum" rule for trigexpand, expansion of sums (e.g. sin(x + y)) will take place only if trigexpandplus is true.
trigexpandtimes Controls the "product" rule for trigexpand, expansion of products (e.g. sin(2 x)) will take place only if trigexpandtimes is true.
Examples:
(%i1) x+sin(3*x)/sin(x),trigexpand=true,expand;
2 2
(%o1) - sin (x) + 3 cos (x) + x
(%i2) trigexpand(sin(10*x+y));
(%o2) cos(10 x) sin(y) + sin(10 x) cos(y) There are also some inexact matches for trigexpand. Try ?? trigexpand to see them.
(%o1) true (%i2)